JP2013004947A - Interposer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interposer that can suppress electromagnetic interference in a semiconductor package and electromagnetic interference between the semiconductor package and a component or circuit in the vicinity of the semiconductor package by absorbing electromagnetic noise inside the semiconductor package.SOLUTION: An interposer is configured to mount a semiconductor element having an electrode terminal, and has a mounting terminal on a lower surface of the interposer. The interposer includes a wiring board with wirings 7 comprised of a signal line, power source line or ground line to establish connection between the electrode terminal and the mounting terminal. A ferrite film 8 formed by electroless plating is disposed on the wirings 7 along the wirings 7. The ferrite film 8 is a film having a film thickness of 1-20 μm containing at least one of a Ni-Zn-based ferrite or Mn-Zn-based ferrite. The ferrite film and the wirings are disposed at an interval of 0-50 μm.

Description

  The present invention relates to an interposer used for a package of a semiconductor element used in an electronic device, and more particularly to an interposer having a function of removing electromagnetic noise generated from an electronic device or an electronic component.

  Conventionally, the countermeasures against electromagnetic noise of electronic devices have mainly been to deal with the restriction of electromagnetic noise radiated from the device to the outside, that is, the problem of electromagnetic interference with external electronic devices. However, with the progress of high frequency, miniaturization, and multi-functionalization of electronic devices, countermeasures against electromagnetic interference between electronic components or electronic circuits inside the devices are indispensable. Furthermore, due to component mounting and higher wiring density, etc., the electromagnetic environment inside the equipment becomes complex, and it is expected that problems that cannot be handled by existing electromagnetic noise countermeasure components alone will occur. Therefore, electromagnetic noise is absorbed inside a package containing a semiconductor component that is a main noise source (hereinafter referred to as a semiconductor package), and electromagnetic interference between wires in the semiconductor package, or a component in the vicinity of the semiconductor package or Development of technology for suppressing electromagnetic interference with a circuit is required.

  As a packaging technology for semiconductor components, a substrate with a bare chip of a semiconductor element mounted on the upper surface, a terminal for mounting on a circuit board on the lower surface, and a wiring between the electrode of the semiconductor element and the wiring between the mounting terminals, that is, an interposer is used. It has been. FIG. 13 is a side view schematically showing an example of a conventional interposer mounted with an IC chip and mounted on an external circuit board. In FIG. 13, the interposer 30 includes an IC chip 31 that is a semiconductor element on the upper surface, a mounting terminal 33 on the lower surface, and a signal line that connects between the electrode terminal of the IC chip 31 and the mounting terminal 33. A wiring board 32 having wiring made up of a power supply line or ground line is provided and mounted on an external circuit board 34. Further, the wiring substrate 32 and the IC chip 31 are molded with a molding material 35.

  As a technique for suppressing electromagnetic interference, a method of absorbing and blocking electromagnetic noise by a magnetic material is generally known. Conventionally, Patent Documents 1 to 3 describe a method of suppressing electromagnetic interference by integrating a magnetic material in an interposer. For example, in Patent Document 1, an inductor is disposed in an outer layer on the surface opposite to the surface on which the IC chip of the interposer is mounted, and bulk ferrite is embedded in a layer between the inductor and the IC chip, whereby IC The electromagnetic interference between the chip and the inductor is suppressed. In Patent Document 2, in order to protect the MRAM element mounted on the interposer, a magnetic shield layer made of, for example, an Fe-based alloy having a thickness of several tens of μm is formed on the inner layer of the interposer. In Patent Document 3, an inductor having a magnetic layer made of, for example, ferrite powder and resin is formed in the inner layer of the interposer.

On the other hand, as described in Patent Document 4 and the like, the ferrite plated film has a function of effectively absorbing electromagnetic noise due to its loss characteristic in order to maintain high magnetic permeability even in a high frequency band. Ferrite plating is a method in which an aqueous solution containing at least ferrous ions (Fe ²⁺ ) as metal ions is brought into contact with the surface of the substrate to adsorb ferrous ions or other metal hydroxide ions and other metal hydroxide ions onto the substrate surface. Ferrous ions (Fe ³⁺ ) are obtained by oxidizing the ferrous ions adsorbed in this manner, and this causes a ferrite crystallization reaction with metal hydroxide ions in an aqueous solution, thereby forming a ferrite film on the substrate surface. To do. Ferrite plating is an electroless plating using an aqueous solution process, and has a feature that a film having both a relatively high specific resistance and excellent magnetic properties can be obtained without heat treatment.

JP 2009-302803 A JP 2005-158985 A JP 2003-318549 A JP 2004-107107 A

  When taking countermeasures against electromagnetic interference in an interposer, the method of Patent Document 1 cannot be expected to be effective as a countermeasure against electromagnetic interference between the interposer and parts or circuits outside the interposer. Furthermore, since ferrite is bulky, it has a problem that it cannot cope with the thinning of the interposer. In addition, the method of Patent Document 2 is a technique mainly for a magnetic shield at a direct current or a low frequency, and since it is assumed to use a metal material, it cannot be expected to be effective as a countermeasure against high frequency electromagnetic interference. Further, at high frequencies, there is a problem that there is a high risk that crosstalk between wirings will increase due to the magnetic shield. Further, since the method of Patent Document 3 is related to an interposer with a built-in inductor and it is assumed that a nonmagnetic resin mixed with ferrite powder is used, the magnetic characteristics are inferior. There is a problem that the effect of absorbing noise using the loss characteristics of the magnetic material cannot be expected.

  In other words, it absorbs electromagnetic noise inside the semiconductor package, which is the main noise source, and simultaneously suppresses electromagnetic interference in the semiconductor package and electromagnetic interference between the semiconductor package and nearby components and circuits. This is difficult with the prior art of Patent Documents 1 to 3.

  Accordingly, an object of the present invention is an interposer capable of absorbing electromagnetic noise inside a semiconductor package and suppressing electromagnetic interference in the semiconductor package and between the semiconductor package and nearby components and circuits. Is to provide.

  In order to solve the above-described problems, an interposer according to the present invention is configured to be capable of mounting a semiconductor element having an electrode terminal, and includes a mounting terminal for mounting on a circuit board on a lower surface, the electrode terminal and the mounting An interposer having a wiring board having wiring composed of signal lines, power supply lines or ground lines connecting between terminals, and a ferrite film formed by electroless plating in the vicinity of at least one of the wirings The ferrite film is disposed along the wiring, and the ferrite film is a film having a thickness of 1 μm to 20 μm having at least one of Ni—Zn ferrite and Mn—Zn ferrite, and the ferrite film and the wiring are 0 to 50 μm. It is characterized by being arranged at intervals of.

  Here, an interval between the ferrite film and the wiring may be less than 10 μm, and a specific resistance of the ferrite film may be 10 Ωcm or more.

  The interval between the ferrite film and the wiring may be 10 to 50 μm, and the specific resistance of the ferrite film may be less than 10 Ωcm.

  The ferrite film is disposed so as to cover an upper side or a lower side of at least two wirings adjacent to each other in the wiring, and a slit-like portion where the ferrite film does not exist between the wirings adjacent to each other. You may have.

  In the present invention, when the distance between the ferrite film and the wiring is smaller than 10 μm, high-frequency conduction noise propagating through the wiring is effectively removed, and adverse effects such as increased crosstalk due to the ferrite film are minimized. Therefore, the specific resistance of the ferrite film is desirably 10 Ωcm or more.

  In addition, when the distance between the ferrite film and the wiring is 10 μm or more, the specific resistance of the ferrite film is less than 10 Ωcm in order to effectively remove the high frequency conduction noise propagating through the wiring. Furthermore, it is desirable that the distance between the ferrite film and the wiring is 50 μm or less.

  When the ferrite film is arranged so as to cover the upper side or the lower side of two adjacent wires, the ferrite film is provided by providing a slit-like portion where the ferrite film does not exist between the adjacent wires. It is possible to suppress an increase in crosstalk between adjacent wirings due to the film. When this slit is provided, the specific resistance of the ferrite film may be smaller than 10 Ωcm. When a slit is provided, the width of the slit is preferably 10 μm or more in order to suppress an increase in crosstalk, and in order to maintain the conduction noise absorption effect, it is a half of the distance between adjacent wirings. 1 or less is desirable.

  In the present invention, when the specific resistance of the ferrite film is 10 Ωcm or more, the distance between the ferrite film and the wiring is preferably small in order to maximize the effect of suppressing conduction noise. The ferrite film and the wiring may be in contact with each other. When the specific resistance of the ferrite film is smaller than 10 Ωcm, the distance between the ferrite film and the wiring is 10 in order to maximize the effect of suppressing conduction noise and minimize the adverse effects such as an increase in crosstalk due to the ferrite film. About 30 μm is desirable.

  In the present invention, the reason why the thickness of the ferrite film is defined to be 1 μm or more is to obtain a sufficient conduction noise suppressing effect. The reason why the thickness of the ferrite film is specified to be 20 μm or less is that when the thickness exceeds 20 μm, the thickness of the substrate constituting the interposer increases remarkably. In the present invention, the ferrite film is disposed so as to cover the wiring on the surface of the substrate constituting the interposer, disposed under the wiring on the substrate, disposed in the inner layer of the substrate, or those And the total thickness of the ferrite film may be 1 to 20 μm. Further, the ferrite film can be patterned and disposed between the wirings along the wiring.

  In the present invention, the ferrite film is disposed in the vicinity of at least one wiring of a signal line, a power supply line, or a ground line. The conductive noise to be removed in the present invention is a signal line, This is because it can occur in both the power supply line and the ground line, and the wiring from which conduction noise is to be removed differs depending on the operating environment of the interposer. The operating environment includes, for example, a wiring layout of a substrate constituting the interposer, a clock frequency of a semiconductor element mounted on the substrate, a communication frequency when the interposer is mounted in a wireless communication device, and the like. In the present invention, the ferrite film can be disposed in the vicinity of all the wirings, but the ferrite film may be selectively disposed by a method such as masking according to the operating environment of the interposer.

  The ferrite film used in the present invention is a ferrite film formed by electroless plating, that is, a ferrite plating thin film formed by ferrite plating. Ferrite plating is an electroless plating using an aqueous solution process, and can be directly deposited on the printed wiring board constituting the interposer of the present invention, and has a relatively high specific resistance and excellent magnetic properties without heat treatment. It has the feature that a film can be obtained. In order to maintain a high permeability even in a high frequency band, the ferrite plating thin film is formed directly on the wiring as close as possible to the semiconductor element that is the source of electromagnetic noise as in the present invention, so that the loss characteristics of the ferrite plating thin film Therefore, electromagnetic noise can be effectively absorbed.

  Thus, noise can be absorbed at a position closer to the source of electromagnetic noise, and electromagnetic interference inside the semiconductor package or electronic device can be suppressed. Accordingly, for example, in a wireless communication device such as a mobile phone terminal, it is possible to eliminate a problem that communication quality deteriorates due to electromagnetic noise generated in the terminal.

  In addition, since the specific resistance of the ferrite film used in the present invention is relatively high, adverse effects caused by the ferrite film being disposed in the vicinity of the wiring on the substrate, such as reflection of electromagnetic noise and increase of crosstalk, re-radiation of electromagnetic noise, etc. There are few merits, and there is a big merit compared with the electromagnetic interference suppression measures using the shield material with high conductivity, such as the conventional metal.

  Further, since the ferrite film used in the present invention has a high noise suppressing effect even at a thickness of 1 to 20 μm, the increase in the substrate thickness due to the ferrite film can be reduced, so that conventional bulk ferrite can be attached to the substrate or magnetic This is more advantageous than a method of attaching a mixture of powder and resin to a substrate.

  The present invention adjusts the frequency characteristics of the complex permeability by changing the composition of the Ni—Zn ferrite film or Mn—Zn ferrite film used as the ferrite film, and the conduction noise suppression effect is enhanced at a desired frequency. Can be adjusted as follows.

  As described above, according to the present invention, electromagnetic noise can be absorbed inside the semiconductor package, and electromagnetic interference in the semiconductor package and between the semiconductor package and the nearby components and circuits can be suppressed. An interposer is obtained.

The perspective view which shows typically a part of wiring board of the 1st-3rd embodiment of the interposer by this invention. The side view which shows typically the manufacturing method of the ferrite film used for the Example regarding the wiring board of the 1st-3rd embodiment of the interposer by this invention. The figure which shows the actual measurement result of the transmission characteristic of the Example regarding the wiring board of 1st Embodiment of the interposer by this invention, and a comparative example. The figure which shows the measurement result of the transmission characteristic of the wiring board of the Example concerning the 2nd Embodiment of the interposer by this invention. The figure which shows the actual measurement result of the transmission characteristic of the wiring board of the Example concerning the 3rd Embodiment of the interposer by this invention, and a comparative example. The perspective view which shows the simulation wiring board made into the object of the crosstalk evaluation of the interposer by this invention. The figure which shows an example of the result of having calculated the amount of crosstalk when changing the specific resistance of the ferrite film of the interposer by this invention. Sectional drawing which shows the simulation wiring board made into the object of crosstalk evaluation of the interposer by this invention. The figure which shows an example of the result of having calculated the amount of crosstalk at the time of changing the magnitude | size (gap) of the space | gap layer between the wiring base | substrate of the interposer by this invention, and a ferrite film. The perspective view which shows the simulation wiring board made into the object of the crosstalk evaluation of the interposer by this invention. Sectional drawing which shows the simulation wiring board made into the object of crosstalk evaluation of the interposer by this invention. The figure which shows an example of the result of having calculated the amount of crosstalk when changing the width | variety of the slit of the ferrite film of the wiring board of the interposer by this invention. The side view which shows typically an example of the conventional interposer which mounted IC chip and was mounted in the external circuit board.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view schematically showing a part of a wiring board of an interposer according to a first embodiment of the present invention. The interposer according to the present embodiment is configured to be able to mount an IC chip having electrode terminals, and includes a mounting terminal for mounting on a circuit board on a lower surface, and connects between the electrode terminal and the mounting terminal. FIG. 1 shows a part of a wiring board that constitutes the interposer. The interposer includes a wiring board that includes wiring composed of signal lines, power supply lines, or ground lines. That is, a part of the wiring board of the interposer according to the present embodiment includes the wiring substrate 3 and the ferrite film 8 disposed on the wiring 7 provided on the wiring substrate 3. As shown in FIG. 1, the wiring 7 is a wiring for connecting the electrode terminal for an IC chip having a small wiring pitch PI and the electrode terminal on the mounting terminal side having a large wiring pitch PO, and the wiring length is L. The ferrite film 8 is provided in a portion other than the both end portions, and the length of the ferrite film is LF. In this embodiment, a Ni—Zn based ferrite film is used as the ferrite film.

  Next, a second embodiment of the interposer according to the present invention will be described. The wiring substrate of the interposer of this embodiment also uses the same wiring substrate 3 as that of the first embodiment shown in FIG. 1, and a ferrite film is similarly disposed on the wiring 7, but the composition of the ferrite film is This is different from the first embodiment. That is, in the present embodiment, a Mn—Zn ferrite film is used as the ferrite film.

  Next, a third embodiment of the interposer according to the present invention will be described. Also in the wiring board of the interposer of the present embodiment, the same wiring substrate 3 as that of the first embodiment shown in FIG. 1 is used, and a ferrite film is disposed on the wiring 7, but in this embodiment, The difference is that the ferrite film is disposed on the wiring 7 with an interval between the wiring 7 and an insulating film.

Example 1
Next, a specific example (hereinafter referred to as Example 1) of the wiring board of the interposer of the present embodiment will be described. In the wiring substrate 3, a wiring 7 produced by patterning a copper wiring layer is formed on a polyimide film 6 having a thickness of 50 μm. In this embodiment, a ferrite film 8 formed by electroless plating is directly disposed on the wiring 7 of the wiring substrate 3. In this embodiment, the wiring length L is 5 mm, the ferrite film length LF is 3 mm, the wiring width W is 6 mm, the wiring pitch PI is 300 μm, and the wiring pitch PO is 650 μm.

Next, a method for producing the ferrite film 8 of Example 1 will be described. FIG. 2 is a side view schematically showing a method of manufacturing a ferrite film used in an example related to the wiring board of the first embodiment of the interposer according to the present invention. As shown in FIG. 2, the wiring substrate 3 on which wiring is formed is placed on the turntable 14 of the film forming apparatus, and deoxygenated ion exchange water is supplied while rotating around the central axis 10 of the turntable 14. While heating to 90 ° C. Subsequently, nitrogen gas was introduced into the apparatus to form a deoxygenated atmosphere. Next, a reaction solution in which desired amounts of FeCl ₂ .4H ₂ O, NiCl ₂ .6H ₂ O, and ZnCl ₂ are dissolved in deoxygenated ion-exchanged water, and NaNO ₂ and CH ₃ COONH ₄ in deoxygenated ion-exchanged water are added. Oxidizing solutions in which desired amounts were dissolved were respectively supplied from the reaction solution nozzle 1 and the oxidizing solution nozzle 2 to the wiring substrate 3 at a flow rate of 40 ml / min. Thereafter, a black ferrite film was formed on the wiring substrate 3 taken out, and it was confirmed by X-ray diffraction that it was a spinel structure single-phase ferrite film. Further, it is a Ni—Zn ferrite film having a composition of Ni _0.2 Zn _0.3 Fe _2.5 O ₄ mainly composed of Ni, Zn, Fe, and O by a scanning electron microscope (SEM-EDS). Confirmed and determined the film thickness. In addition, the real part μ ′ of the complex permeability of the obtained film was substantially constant with respect to the frequency at a low frequency of about 100 MHz or less, and the value thereof was about 40. Further, the imaginary part μ ″ of the complex magnetic permeability is almost 0 at a low frequency of about 100 MHz or less, rises from around 100 MHz, reaches a maximum value of about 30 at about 350 MHz, and at a higher frequency, the measurement frequency limit of the apparatus. It gradually decreased to a certain 3 GHz and showed a relatively high value of about 10. Even at 3 GHz, it was confirmed that the specific resistance of the obtained film was 1 × 10 ³ Ωcm.

  Next, examples of the wiring board in which the thickness of the ferrite film was 1 μm, 3 μm, and 20 μm and a comparative example in which the thickness was 0.5 μm were prepared, and the transmission characteristic S21 was evaluated. As shown in FIG. 1, the measurement was performed by connecting both ends of the central two wires in the wire 7 to the port 1 and the port 2 of the network analyzer via microprobes, respectively. The input impedance of both port 1 and port 2 is 50Ω. FIG. 3 is a diagram showing measurement results of transmission characteristics of an example and a comparative example related to the wiring board of the first embodiment of the interposer according to the present invention. The comparative example with a film thickness of 0.5 μm does not show a significant difference from the case without the ferrite film, but the examples with the film thickness of 1 μm, 3 μm and 20 μm have a higher frequency band than the case without the ferrite film. Attenuation is noticeably observed at, and the amount of attenuation increases as the film thickness increases.

(Example 2)
Next, a specific example (hereinafter referred to as Example 2) of the wiring board of the interposer of the present embodiment will be described. Also in Example 2, the arrangement and shape of the wiring substrate 3, the wiring 7, and the ferrite film 8 are the same as in Example 1, the wiring length L is 5 mm, the ferrite film length LF is 3 mm, the wiring width W is 6 mm, the wiring The pitch PI is 300 μm, and the wiring pitch PO is 650 μm. A method for producing the ferrite film of this example will be described below. As shown in FIG. 2, as in Example 1, the wiring substrate 3 was placed on the turntable 14 of the film forming apparatus, and heated to 90 ° C. while supplying deoxygenated ion exchange water while rotating. Subsequently, nitrogen gas was introduced into the apparatus to form a deoxygenated atmosphere. A reaction solution in which desired amounts of FeCl ₂ .4H ₂ O, MnCl ₂ .4H ₂ O, and ZnCl ₂ were dissolved in deoxygenated ion-exchanged water, and CH ₃ COONa and (NH ₄ ) ₂ CO _{3 in} deoxygenated ion-exchanged water, respectively. Then, an oxidizing solution in which desired amounts of NaNO ₂ and NaOH were dissolved was supplied from the reaction solution nozzle 1 and the oxidizing solution nozzle 2 to the wiring substrate 3 at a flow rate of 40 ml / min. Thereafter, a black ferrite film was formed on the wiring substrate 3 taken out, and it was confirmed by X-ray diffraction that it was a spinel structure single-phase ferrite film. Further, it is a Mn—Zn ferrite film having a composition Mn _0.2 Zn _0.3 Fe _2.5 O ₄ mainly composed of Mn, Zn, Fe, and O by a scanning electron microscope (SEM-EDS). Confirmed and determined the film thickness. Further, the real part μ ′ of the complex permeability of the obtained film was substantially constant with respect to the frequency at a low frequency of about 100 MHz or less, and the value thereof was about 40. Further, the imaginary part μ ″ of the complex magnetic permeability is almost 0 at a low frequency of about 100 MHz or less, rises from around 100 MHz, reaches a maximum value of about 30 at about 350 MHz, and at a higher frequency, the measurement frequency limit of the apparatus. It gradually decreased to a certain 3 GHz, and showed a relatively high value of about 10 even at 3 GHz, and it was confirmed that the specific resistance of the obtained film was 1 × 10 ⁴ Ωcm.

  A wiring board was produced with a ferrite film thickness of 3 μm, and the transmission characteristic S21 between both ends of the central two wirings in the wiring 7 was measured by the same method as in Example 1. FIG. 4 is a diagram showing the actual measurement results of the transmission characteristics of the wiring board of the example according to the second embodiment of the interposer according to the present invention. Also in the Mn—Zn based ferrite film of this example, almost the same attenuation as in the case of the Ni—Zn based ferrite film having a thickness of 3 μm was observed.

(Example 3)
Next, a specific example (hereinafter referred to as Example 3) of the wiring board of the interposer of the present embodiment will be described. Also in the third embodiment, the wiring substrate 3, the wiring 7, and the ferrite film are different in that the ferrite film is arranged on the wiring 7 with a certain distance between the wiring 7 and the wiring 7. The arrangement and shape of 8 and the like are the same as those in Example 1, the wiring length L is 5 mm, the ferrite film length LF is 3 mm, the wiring width W is 6 mm, the wiring pitch PI is 300 μm, and the wiring pitch PO is 650 μm. In the manufacturing method of the wiring board of this example, an insulating solder resist film was first formed on the wiring 7 of the wiring substrate 3, and a ferrite film was formed on the solder resist film. The same Ni—Zn-based ferrite film as in Example 1 was produced by the same manufacturing method as in Example 1. It was confirmed that the obtained ferrite film had the same composition as the ferrite film of Example 1 and had the same complex magnetic permeability frequency characteristics. The specific resistance of the film was confirmed to be 1 × 10 ³ Ωcm.

  The example of the wiring board with a ferrite film thickness of 3 μm, the solder resist film thickness of 10 μm and 50 μm and the comparative example of the wiring board with a ferrite film thickness of 60 μm were prepared, and the same as in Example 1 The transmission characteristic S21 between the two ends of the central two wires in the wire 7 was evaluated by the above method. FIG. 5 is a diagram showing the measurement results of the transmission characteristics of the wiring boards of the example and the comparative example according to the third embodiment of the interposer according to the present invention. In the case of the comparative example in which the film thickness of the solder resist film, that is, the distance between the ferrite film and the wiring 7 is 60 μm, the difference from the case without the ferrite is not noticeable, but the distance between the ferrite film and the wiring 7 is In the examples of 10 μm and 50 μm, the attenuation in the high frequency band is conspicuous as compared with the case without ferrite, and the amount of attenuation increases as the distance between the ferrite film and the wiring 7 decreases.

  Next, in the case where the ferrite film is arranged directly on the wiring 7 as in the above-described Example 1 and Example 2, the evaluation of the crosstalk generated between the wirings on the wiring board is performed using a finite element method. The results of the electromagnetic field simulation will be described. FIG. 6 is a perspective view showing a simulated wiring board that is an object of crosstalk evaluation of an interposer according to the present invention. The wiring substrate 4 is obtained by arranging a copper foil 5 having a thickness of 18 μm as a ground on the back surface of the wiring substrate 3 shown in FIG. 1, that is, under a polyimide film 6 having a thickness of 50 μm. A copper wiring 7 is formed on the polyimide film 6 as in FIG. 1, and a ferrite film 8 is formed directly on the wiring 7. The arrangement and shape of the wiring substrate 3, the wiring 7, the ferrite film 8, etc. are the same as in Example 1. The wiring length L is 5 mm, the ferrite film length LF is 3 mm, the wiring width W is 6 mm, the wiring pitch PI is 300 μm, the wiring The pitch PO is 650 μm. As shown in FIG. 6, when a signal is input to one end of one of the two central wirings in the wiring 7 and the ground on the lower surface, that is, when a signal is input to the port 1, The magnitude of the signal leaking into port 2 due to crosstalk was calculated. It is assumed that an IC chip is mounted on the port 1 side or the port 2 side, and the other end of the wiring is terminated with a 50Ω resistor.

  FIG. 7 is a diagram showing an example of the result of calculating the crosstalk amount when the specific resistance of the ferrite film of the interposer according to the present invention is changed. The ferrite film thickness is 3 μm, the relative permeability of the ferrite film is μ ′ = 40, μ ″ = 0, the relative permittivity of the ferrite film is ε ′ = 60, ε ″ = 0, and the specific resistance of the ferrite film is changed. It is the result of calculating the amount of crosstalk in the case of. The specific resistance of the ferrite film was changed to 0.1Ωcm, 1Ωcm, 10Ωcm, and 1000Ωcm. As the specific resistance of the ferrite film is lower, the amount of crosstalk increases. However, it can be seen that if the specific resistance of the ferrite film is 10 Ωcm or more, the increase in crosstalk is suppressed.

  Next, in the case where a ferrite film is arranged on the wiring 7 with an interval as in the above-described third embodiment, the evaluation of crosstalk generated between the wirings of the wiring board is performed using a three-dimensional electromagnetic method using a finite element method. The results of the field simulation will be described. FIG. 8 is a cross-sectional view showing a simulated wiring board which is an object of crosstalk evaluation of an interposer according to the present invention. The wiring substrate 4 is the same as the wiring substrate 4 shown in FIG. 6, in which a copper foil 5 having a thickness of 18 μm is disposed as a ground under the polyimide film 6. However, here, as shown in FIG. 8, the ferrite film 8 is formed on the wiring 7 via the gap layer 9. As in FIG. 6, the calculation is performed between one end of the central two wirings in the wiring 7 and the ground on the lower surface, that is, when a signal is input to the port 1, between the other adjacent one end and the ground on the lower surface. That is, the magnitude of the signal leaking as crosstalk at port 2 was calculated. The other ends of port 1 and port 2 are terminated with 50Ω resistors.

FIG. 9 is a diagram showing an example of the result of calculating the crosstalk amount when the size (gap) of the gap layer between the wiring substrate and the ferrite film of the interposer according to the present invention is changed. The ferrite film thickness is 3 μm, the resistivity of the ferrite film is 10 ⁻¹ Ωcm, the relative permeability of the ferrite film is μ ′ = 40, μ ″ = 0, the relative permittivity of the ferrite film is ε ′ = 60, ε ″ = 0 And the amount of crosstalk when the size of the gap layer 9 is changed. The size of the void layer was 5 μm, 10 μm, 20 μm, 40 μm, and 60 μm. Note that the relative permeability of the void layer was μ ′ = 1, μ ″ = 0, and the relative dielectric constant of the void layer was ε ′ = 1, ε ″ = 0. As shown in FIG. 9, when the size of the gap layer 9 is 10 μm or more, the increase in crosstalk due to the ferrite film is suppressed to a low level.

  Next, in the case where a ferrite film is directly disposed on the wiring 7 and a slit-like portion where no ferrite film is present is provided between two adjacent wirings, evaluation of crosstalk generated between the wirings is performed using a finite element. The results of the three-dimensional electromagnetic field simulation using the method will be described. FIG. 10 is a perspective view showing a simulated wiring board targeted for crosstalk evaluation of an interposer according to the present invention, and FIG. 11 is a cross section showing a simulated wiring board targeted for crosstalk evaluation of an interposer according to the present invention. FIG. The wiring substrate 4 is the same as the wiring substrate 4 shown in FIG. 6, in which a copper foil 5 having a thickness of 18 μm is disposed as a ground under the polyimide film 6. The ferrite film 18 is directly disposed on the wiring 7. However, here, as shown in FIGS. 10 and 11, the center port 1 and the port 2 in the wiring 7 are provided on the ferrite film 18. A slit 19 is provided between the constituent wirings. In the calculation of crosstalk, the magnitude of a signal leaked as crosstalk to the adjacent port 2 when a signal was input to the port 1 was calculated in the same manner as described above. The other ends of port 1 and port 2 are terminated with 50Ω resistors.

FIG. 12 is a diagram showing an example of the result of calculating the crosstalk amount when the slit width of the ferrite film of the wiring board of the interposer according to the present invention is changed. The ferrite film thickness is 3 μm, the resistivity of the ferrite film is 10 ⁻¹ Ωcm, the relative permeability of the ferrite film is μ ′ = 40, μ ″ = 0, the relative permittivity of the ferrite film is ε ′ = 60, ε ″ = 0 And the amount of crosstalk when the width of the slit 10 of the ferrite film 19 is changed is calculated. The slit width was changed to 10 μm, 50 μm, and 100 μm. As shown in FIG. 12, when the width of the slit 10 is 10 μm or more, the increase in crosstalk due to the ferrite film is suppressed to a low level.

  Needless to say, the present invention is not limited to the above-described embodiments, and the design can be changed in accordance with semiconductor elements mounted on the interposer, noise to be suppressed, and the like. For example, the shape, material, configuration, wiring pattern, layer structure, installation location of the ferrite film, and target wiring can be arbitrarily selected.

DESCRIPTION OF SYMBOLS 1 Reaction liquid nozzle 2 Oxidizing liquid nozzle 3, 4 Wiring substrate 5 Copper foil 6 Polyimide film 7 Wiring 8, 18 Ferrite film 9 Gap layer 10 Center axis 14 Rotary table 19 Slit 30 Interposer 31 IC chip 32 Wiring board 33 Mounting terminal 34 External circuit board 35 Mold material

Claims (4)

  A signal line, a power supply line, or a ground line configured to be capable of mounting a semiconductor element having an electrode terminal, provided with a mounting terminal for mounting on a circuit board on a lower surface, and connecting between the electrode terminal and the mounting terminal An interposer having a wiring board comprising wiring comprising: a ferrite film formed by electroless plating in the vicinity of at least one wiring of the wiring is disposed along the wiring, and the ferrite film is made of Ni- An interposer, which is a film having a film thickness of 1 μm to 20 μm having at least one of Zn-based ferrite or Mn—Zn-based ferrite, and wherein the ferrite film and the wiring are arranged at an interval of 0 to 50 μm.   2. The interposer according to claim 1, wherein an interval between the ferrite film and the wiring is less than 10 μm, and a specific resistance of the ferrite film is 10 Ωcm or more.   2. The interposer according to claim 1, wherein an interval between the ferrite film and the wiring is 10 to 50 μm, and a specific resistance of the ferrite film is less than 10 Ωcm.   The ferrite film is disposed so as to cover an upper side or a lower side of at least two adjacent wirings of the wiring, and has a slit-like portion where the ferrite film does not exist between the adjacent wirings. The interposer according to any one of claims 1 to 3, wherein

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